import java.util.Scanner;

public class 学生成绩 {
    public static void main(String[] args) {
        Scanner grade=new Scanner(System.in);
        System.out.println("请输入成绩：");
        Double grades=grade.nextDouble();
        if(grades>=0&&grades<=59){
            System.out.println("C");

        }else if(grades>=60&&grades<=80){
            System.out.println("B");
        }else if(grades>=81&&grades<=100){
            System.out.println("A");
        }else {
            System.out.println("成绩输入有误，请重新输入");
        }
    }
}
